Add prefilters only once in the compound and text similarity retrievers (#114983)

This change ensures that the prefilters are propagated in the downstream retrievers only once.
It also removes the ability to extends `explainQuery` in the compound retriever. This is not needed
as the rank docs are now responsible for the explanation.

Author: jimczi

server/src/main/java/org/elasticsearch/search/retriever/CompoundRetrieverBuilder.java

@@ -18,7 +18,6 @@
 import org.elasticsearch.action.search.SearchRequest;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.search.TransportMultiSearchAction;
-import org.elasticsearch.index.query.BoolQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.index.query.QueryRewriteContext;
 import org.elasticsearch.search.builder.PointInTimeBuilder;
@@ -163,6 +162,11 @@ public final QueryBuilder topDocsQuery() {
         throw new IllegalStateException("Should not be called, missing a rewrite?");
     }
 
+    @Override
+    public final QueryBuilder explainQuery() {
+        throw new IllegalStateException("Should not be called, missing a rewrite?");
+    }
+
     @Override
     public final void extractToSearchSourceBuilder(SearchSourceBuilder searchSourceBuilder, boolean compoundUsed) {
         throw new IllegalStateException("Should not be called, missing a rewrite?");
@@ -216,22 +220,12 @@ protected SearchSourceBuilder createSearchSourceBuilder(PointInTimeBuilder pit,
             .trackTotalHits(false)
             .storedFields(new StoredFieldsContext(false))
             .size(rankWindowSize);
+        // apply the pre-filters downstream once
         if (preFilterQueryBuilders.isEmpty() == false) {
             retrieverBuilder.getPreFilterQueryBuilders().addAll(preFilterQueryBuilders);
         }
         retrieverBuilder.extractToSearchSourceBuilder(sourceBuilder, true);
 
-        // apply the pre-filters
-        if (preFilterQueryBuilders.size() > 0) {
-            QueryBuilder query = sourceBuilder.query();
-            BoolQueryBuilder newQuery = new BoolQueryBuilder();
-            if (query != null) {
-                newQuery.must(query);
-            }
-            preFilterQueryBuilders.forEach(newQuery::filter);
-            sourceBuilder.query(newQuery);
-        }
-
         // Record the shard id in the sort result
         List<SortBuilder<?>> sortBuilders = sourceBuilder.sorts() != null ? new ArrayList<>(sourceBuilder.sorts()) : new ArrayList<>();
         if (sortBuilders.isEmpty()) {

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/rank/textsimilarity/TextSimilarityRankRetrieverBuilder.java

@@ -10,7 +10,6 @@
 import org.apache.lucene.search.ScoreDoc;
 import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.features.NodeFeature;
-import org.elasticsearch.index.query.BoolQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.license.LicenseUtils;
 import org.elasticsearch.search.builder.PointInTimeBuilder;
@@ -20,7 +19,6 @@
 import org.elasticsearch.search.retriever.CompoundRetrieverBuilder;
 import org.elasticsearch.search.retriever.RetrieverBuilder;
 import org.elasticsearch.search.retriever.RetrieverParserContext;
-import org.elasticsearch.search.retriever.rankdoc.RankDocsQueryBuilder;
 import org.elasticsearch.xcontent.ConstructingObjectParser;
 import org.elasticsearch.xcontent.ParseField;
 import org.elasticsearch.xcontent.XContentBuilder;
@@ -158,33 +156,18 @@ protected RankDoc[] combineInnerRetrieverResults(List<ScoreDoc[]> rankResults) {
         return textSimilarityRankDocs;
     }
 
-    @Override
-    public QueryBuilder explainQuery() {
-        // the original matching set of the TextSimilarityRank retriever is specified by its nested retriever
-        return new RankDocsQueryBuilder(rankDocs, new QueryBuilder[] { innerRetrievers.get(0).retriever().explainQuery() }, true);
-    }
-
     @Override
     protected SearchSourceBuilder createSearchSourceBuilder(PointInTimeBuilder pit, RetrieverBuilder retrieverBuilder) {
         var sourceBuilder = new SearchSourceBuilder().pointInTimeBuilder(pit)
             .trackTotalHits(false)
             .storedFields(new StoredFieldsContext(false))
             .size(rankWindowSize);
+        // apply the pre-filters downstream once
         if (preFilterQueryBuilders.isEmpty() == false) {
             retrieverBuilder.getPreFilterQueryBuilders().addAll(preFilterQueryBuilders);
         }
         retrieverBuilder.extractToSearchSourceBuilder(sourceBuilder, true);
 
-        // apply the pre-filters
-        if (preFilterQueryBuilders.size() > 0) {
-            QueryBuilder query = sourceBuilder.query();
-            BoolQueryBuilder newQuery = new BoolQueryBuilder();
-            if (query != null) {
-                newQuery.must(query);
-            }
-            preFilterQueryBuilders.forEach(newQuery::filter);
-            sourceBuilder.query(newQuery);
-        }
         sourceBuilder.rankBuilder(
             new TextSimilarityRankBuilder(this.field, this.inferenceId, this.inferenceText, this.rankWindowSize, this.minScore)
         );